If you are getting gas struts from a scrapyard make sure you get them off a car with a spoiler fitted, as they are a bit more powerful because of the extra weight.
It is probably only one of your struts which has failed, but it is hard to tell which one it is.
Jill
May 2011
go to a scrap yard and get some more struts from a vectra same model as yours
wardy
May 2011
Sounds as if you need to replace your tailgate struts.